Last-ditch DNA battle to save Tasmanian devil from extinction at hands of contagious cancer spread by biting

By Rob Waugh
Updated: 12:00 EST, 16 February 2012


The Tasmanian devil is the only animal on Earth at risk of being wiped out by a contagious cancer

The Tasmanian devil is the only animal on Earth at risk of being wiped out by a contagious cancer

Researchers have sequenced the genome of a contagious cancer that is threatening the Tasmanian devil, the world's largest carnivorous marsupial, with extinction.

The Tasmanian devil is the only animal on Earth at risk of being wiped out by a contagious cancer.

The cancer, which is spread by biting, came from the cells of a single female Tasmanian devil, nicknamed 'The Immortal Devil' because although she died more than 15 years ago, her DNA is living on in the contagious cancer cell line that she spawned.

The cancer causes tumours on the face of affected devils.

The tumours grow rapidly and the devils die within months.

'The Tasmanian devil cancer is the only cancer that is threatening an entire species with extinction,' says Dr Elizabeth Murchison, lead author from the Wellcome Trust Sanger Institute.

'Sequencing the genome of this cancer has allowed us to catalogue the mutations that caused this cancer to arise and to persist in the Tasmanian devil population.'

'Cancers that transmit through populations are obviously incredibly rare, but we should use the Tasmanian devil example to understand the process to be prepared in the extremely unlikely event that such an epidemic ever occurs in humans,' says Professor Mike Stratton, senior author and Director of the Wellcome Trust Sanger Institute.

The team found evidence for genetic differences between tumours, indicating that the cancer has changed during its spread through the Tasmanian devil population.

They searched for these genetic differences between the tumours of 69 different devils from distant locations in Tasmania, allowing them to build up a map of the cancer's spread through the devil population.

Endangered: Scientists are using hi-tech DNA-sequencing in a desperate attempt to stave off devil facial tumour disease and save the Tasmanian devil from extinction

Endangered: Scientists are using DNA-sequencing in a desperate attempt to stave off devil facial tumour disease and save the Tasmanian devil from extinction

This indicates that some cancer sub-types may be more virulent than others.

'We found that devil cancer's genome has about 20,000 mutations. This is fewer mutations than are found in some human cancers and indicates that cancers do not need to be extremely unstable in order to become contagious.' says Dr David Bentley, senior co-author from Illumina Cambridge Ltd.

Tracing the evolutionary history and spread of this cancer helps us to understand not only what caused this disease but also to predict how it might behave in the future.'